1. Field of the Invention
This invention relates to a water-in-oil-type cosmetic and, more particularly, to a water-in-oil-type make-up cosmetic, which possesses an excellent emulsion stability, imparts a refreshing feeling to the skin upon application, and can be well retained on the skin after application.
2. Description of the Background Invention
Foundations, eye liners, mascaras, and the like are included in emulsion-type cosmetics for make-up use. They are classified into oil-in-water-type cosmetics (hereinafter referred to as "o/w type cosmetics") and water-in-oil-type cosmetics (hereinafter referred to as "w/p-type cosmetics") depending on the type of emulsion employed.
As compared with oil-based cosmetics, these emulsion-type cosmetics impact a sense of refreshment and are less oily when applied to the skin because water is incorporated as their component. Additional features of the emulsion-type cosmetics are that they are prepared mostly in liquid or cream form and are well extendible on the skin, providing an evenly finished make-up.
In particular, as compared with o/w type cosmetics, w/o-type cosmetics, being of a continuous oil phase, have a higher resistance to bacteria, form an oil film with a low water-permeability on the skin, which can protect the skin from becoming dry over a long period of time and does not re-emulsify when the same comes into contact with water on such occasions as swimming, washing, kitchen work, or sweating, thus preventing the make-up from running, cracking or becoming spottedly discolored.
It has conventionally been difficult to formulate a stable w/o-type emulsion. In order to make a stable emulsion, it is sometimes necessary to restrict the amount of water to be incorporated in the dispersion phase or to employ an oil component with a higher viscosity for the continuous phase. This brings about drawbacks in which the cosmetics produce a stickiness or strong oily feeling upon use.
For providing an emulsion cosmetic with better capability to refresh the user upon use, it is imperative that the cosmetic contain a smaller amount of low viscosity oil components.
Polysiloxanes (hereinafter sometimes referred to as "silicone oils") of formulae (II), (III) and (IV) hereinafter described are suitable oil components for cosmetics since they are capable of forming a thin, homogeneous film on the skin and imparting a less sticky, smoother feeling. These silicone oils, however, are insufficiently compatible with commonly used surface active agents and other oil components. Furthermore, they are not readily emulsifiable so that it is very difficult to obtain a fine homogeneous, emulsion from them.
Another effective way of providing a cosmetic with good refreshing capability upon use is to incorporate ethyl alcohol in it. Addition of ethyl alcohol to an emulsion, however, greatly impairs the stability of the emulsion system.
Because of these reasons, the wide, popular use of w/o-type cosmetics is restricted in spite of their advantages over o/w-type cosmetics. Therefore, development of w/o-type cosmetics featuring higher stability and the provision of a better, more refreshing feeling upon use has long been desired.
In light of this background, the present inventors have conducted extensive studies for overcoming the above-mentioned problems in preparing w/o-type cosmetics. As a result, the inventors found that a highly stable w/o-type cosmetic which gives a fine refreshing feeling upon use, and which can be well retained on the skin after application, can be prepared by using a specific type of dimethylpolysiloxanepolyoxyalkylene copolymer as an emulsifier; by providing an oil phase comprising a silicone oil and a cosmetic powder the surface of which is treated to make the same water-repellent; and by adding to this oil phase a water phase containing a specified proportion of ethyl alcohol. These findings have led to the completion of this invention.